1. Field of the Invention
This invention relates to a cooling air bleed device in a turbine engine, such as an airplane turbojet, which is intended in particular for cooling flaps of a convergent-divergent jet nozzle.
The jet nozzle of a turbojet generally comprises mobile flaps that are subjected to strong thermal stresses due to the passage of very hot gases coming from the combustion chamber of the turbomachine. These thermal stresses generate large amounts of infrared radiation capable of hindering the stealth of military aircraft and that should be minimized.
A solution consists of bleeding cold air in a secondary flow of the turbomachine, so as to direct it toward the flaps of the nozzle and cool them.
2. Description of the Related Art
The patent application EP 1 522 680 of the applicant describes a system for ventilating mobile flaps of a convergent-divergent nozzle of an airplane turbojet, which system includes an annular conduit supplied with cooling air through orifices provided in a wall separating the interior of the conduit from the downstream end of an annular passage surrounding a post-combustion chamber of the turbojet and in which a cooling airflow circulates. This ventilation system also includes air distribution cells distributed around the conduit and connected thereto, and telescopic channels each connecting a cell to a divergent nozzle seal located in the same plane of symmetry as the cell.
The disadvantage of this system is that it does not enable the bled airflow to be modulated.
This air bleed adversely affects the performance of the turbojet and is generally unnecessary in all phases of the aircraft flight.